The increasing popularity of smart micro mobile devices in daily life is closely related to the developments in the field of APP application programs in recent years. APP application programs can achieve smart interactive functions mainly because of the continuous evolution in sensing technology for human-computer interaction with the environment. By adding various sensors in the smart micro mobile device, environmental sensing information can be promptly provided for users to accomplish diverse life applications. Among all types of sensors, development of a MEMS gas sensor is by far the most compelling.
A sensing method used in a present MEMS gas sensor is to apply different electrical voltages to a heater so the heater can heat a sensing material thereby allowing the sensing material to reach preset operating temperatures of different gases. However, when a temperature of the sensing material changes due to external environment factors or other factors and the sensing material is therefore unable to operate at an optimal operating temperature, any types of the gas to be measured can affect output of the sensing material as the result. Therefore, it is unable to clearly recognize what type of the gases and a concentration thereof which induces the change in a sensing signal. In general, the electrical voltage is applied to the heater for a constant period of time to ensure that the temperature of the sensing material can reach the preset operating temperature and maintain constantly at the preset operating temperature. Yet, in the process of driving the heater to heat the sensing material, there may still be a difference between the preset operating temperature and the actual operating temperature. As such, although the aforementioned method can maintain the actual operating temperature at constant level, the preset operating temperature will not always be equal to the actual operating temperature. In addition, because the approach of providing the electrical voltage for the constant period of time to drive the heater can also provide excess heat, electrical power consumption of the MEMS gas sensor cannot be effectively reduced.